A large number of patents are directed to the production of electrolytic capacitors which are primarily used where high specific storage capacity is required. The dielectric used is generally an oxide of one of Al, Ta, Ti, and the like or, in other words, a material having excellent insulating characteristics. Existing electrolytic capacitors have high specific storage capacity due to these dielectrics.
A subsequent development is expected by experts to increase by different methods the surfaces of positive electrodes (by making aluminum foil spongy for instance). It is the unequivocal opinion of some experts that specific storage capacity depends geometrically on specific surface only.
In addition to the specific surface, however, other geometrical factors have not been accounted for, and as will be later seen, their part is important enough. It is believed that the influence of geometric factors and the advantages of regular orientation have not been sufficiently taken into consideration.
By way of information, German Pat. No. 1,464,816 might be mentioned. Though not relating to an electrolytic capacitor, nevertheless regular orientation has here already a part. Obviously, thin elementary threads, their orientation, and their utilization in the electrolytic capacitors are for themselves unimportant, but may determine the way.
The regular geometrical form, in this case a cylinder or its radius (r.sub.1), is to be brought in a special way into a relationship with the applied maximum operating voltage (U) and with the known maximum field strength (E.sub.m) of the dielectric.
From the point of view of specific storage capacity or energy content, optimal determination of the relation of the above three factors with respect to each other is important, but not the specific surface.
From mathematical verification and from graphical representations, it will be later seen that increasing the specific surface beyond a certain limit does not increase, but instead rapidly diminishes, the specific storage capacity.